Posted by jtown on November 06, 2001 at 09:09:29:
In Reply to: How do I know if main vents are working? posted by Mitch Berkson on November 06, 2001 at 06:54:51:
To test a vent, ensure that system is cool and when pressure is building feel for air being pushed out or try a LITTLE scrap of paper and watch for it to be blown off. Once hot it should be tightly closed until the system cools and the pressure drops. You can try blowing through it while it is cool and vertical. Tipping it over, you should not be able to blow through it. There is a bottle with a little alcohol inside with a flat bottom. The alcohol boils causing pressure. The bottom expands outward pushing up the bottle with it's needle on top. This seals the hole. Also the bottle can float to seal if flooded.